When you have a franchise that's as beloved as Harry Potter, people are sure to latch onto details. Sometimes, it's people just taking things way too seriously, but other times we're talking about moments that appear to be such gaping plot holes that they're all but impossible to ignore. We're going to be talking about the latter today.
Just to be clear, this theory refers to the book. The movie takes some liberties with the story that eliminate this explanation from working.